Relay



S P 1929 o. s. JENNINGS 1,728,551

' Q RELAY Original Filed Aug. 6. i920 5 4 2 8 WITNESSES: 1} 14 9 INVENTOR 3 J oliveradennlhys Patented Sept. 17, 1929 UNITED STATES PATENT OFFICE OLIVER S. JENNINGS, F BROOKLYN, NEW YORK, ASSIGNOB T0 WESTINGHOUSE ELECTRIC 8a MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA RELAY- Application flled August 6, 1920, Serial No. 401,620. Renewed October 22, 1928.

-My invention relates to relays and particularly to thermal relays.-

One object of my invention is to provide a thermal relay for an electric circuit that shall reproduce temperature conditions that correspond to the conditions in apparatus connected to the circuit, and that shall operate to disconnect the apparatus from the circuit when predetermined temperature conditions 10 obtain in the apparatus.

Another object of m invention is to provide a relay device, oi the above-indicated character, that shall be simple and economical in construction and reliable in its operation.

My copending application, Serial No. 401,619; filed August 6, i920, discloses a therrupter to open to disconnect the apparatus from the circuit from which it is normally energized.

In practicing my invention, l provide a magnetizable core member of substantially E-shape having a movable armature member so pivoted on the middle leg portion of the core-member that it may move to engage either of the end leg portions of that member. A'contact member is supported on the magnetizable core member and is adapted to be engaged by a contact member that is mounted on the movable armature member.

The core member has a winding disposed on each end portionthereoi and has a spring so disposed, between the armature member and the core member,- that the contact mem bers are normally maintained in positive engagement. The windings are connected in parallel relation with each other but in series with a conductor of the electrical apperatus that is to be protected. The windings are normally so disposed that their ampere turns or magnetizing forces are equal and opposing. The windings are so proportioned that the respective resistances thereof are different but the ampere turns thereof are the same under normal conditions.

As the windings become heated by the current traversing the same the temperatures developed therein approximate the temperatures obtaining in the electrical apparatus. As the temperature of the windings attains a predetermined value that corresponds to a dangerous operating temperature in the apparatus the armature of the relay becomes so actuate by the resultant magnetizing force as to disengage the two contact members. The circuit of a holding magnet on the circuit interrupter is thereby interrupted and the interrupter is permitted to open to disconnect the apparatus from the source of energy.

Figure l of the accompanying drawings is a diagrammatic view oil an electrical circuit that includes device embodying my invention;

Fig. 2 is a side view partially in elevation and partiwy in section, of a relay embody in my invention;

la e is modified are of the device shown in Fig. 2; and

l igs d and 5 are diagrammatic views of circuits that include modified forms of the device shown in Fig. 2.

An electrical apparatus 1 is adapted to receive energ from. a source 2 of electromotive force tnrough'a circuit-interrupting device 3 that is provided with a holding magnet d and a restraining spring 5. A protective relay 6 is provided to protect the apparatus 1 from overheating by interrupting the circuit of the holding magnet d to release the interrupter 3.

The relay 6 com rises a ma etizable core member 7 oi the su stantially -shape, a movable armature member 8, a spring member 9, two windings 1t) and 11 and two contact members 12 and 13. The armature member 8 is pivoted at a point intermediate the ends thereof on the middle leg portion 140i the V core member 7'and has the contact member 12 adjustably mounted at one end thereof. The spring 9 is so disposed between the core member 7 and the armature member 8 that the contact member 12 is caused to engage the stationary contact member 13 that is mounted on the core member. The windings 10 and 11 are mounted on the end leg portions 15 and 16, respectively, of the core member 7 The windings 10 and 11 are wound with I difl'erent numbers of turns butthe ratio begree by the Joulean, or PR, losses and the re sistance of that winding correspondingly increases more rapidly than the resistance of the other winding. The value of current that may traverse the heated winding is therefore decreased and the value of current that may traverse the second winding is relatively increased with a corresponding change in the ratio between the magnetizing forces that are developed by the respective windings.

' As the relative change in temperature is increased with an increase of current in the apparatus 1, the efi'ective, or resultant, magnetizing force increases. At a predetermined condition in the windings 10 and 11, that corresponds to a dangerous temperature condition in the apparatus 1, the eflective magnetizing force, which, is equivalent to the resultant between the ma netizing forces of the respective windings, ecomes sufficient to actuate the armature 8 against the compression force of the spring 9. The consequent disengagement of the contact members 12 and 13 opens the circuit of the holding magnet t v and permits the interrupter 3 to be opened by the spring 5.

The self and the mutual-inductive effects of the windings are such that the magnetizing forces, instead of being directly opposed, are so disposed that vectors representing the respective forces form an obtuse angle.

Moreover, a degree of unbalance obtains between the values of the magnetizing forces while the relay is traversed by current since the windings become heated thereby'to a certain degree. The occurrence of a short circuit tends to so ,increase the magnetizing forces of the respective windings that the resultant magnetizing force is greatly magnified and the consequent operation of the rela is correspondingly accelerated.

T e increase in the inductive efiects of the windings tends to so change the relation berelay as to render it substantially instanta neous.

In Fig. 3 is illustrated a modified form of the device of Fig. 2, in which both windings are mounted on a common portion of the core member. The spring 9 serves to maintain the contact members 12 and 13 in engagement until predetermined temperature conditions obtain in the windings 10 and 11, where upon the resultant magnetizing force s0 actuates the movable armature member 17 as to effect the disengagement of the contact members. In this form of device, the pivoted armature member 17 is provided with a counterbalancing portion 1 The diagrammatic circuit that is illustrated in Fig.4 illustrates another modification of the device of Fig. 2, in which both windings may have the same number of turns and an external resistor 19 used with one of the windings to control the value of the current that shall traverse the same.

The diagrammatic circuit that is illustrated in Fig. 5 illustrates a further modification wherein each winding is respectively connected in series with a different conductor. Resisters 20 and 21' are connected in parallel with the respective windings l0 and 11 and have such characteristics that the respective windings are so increasingly and decreasingly energized that the relay is caused to operate at a predetermined temperature in the Windings, that corresponds to a dangerous temperature in the apparatus to be protected.

The unbalance that is necessary between the magnetizing forces to effect the operation of the relay be obtained by various methods. The win ings may normally have different values of resistance, as indicated above, and thus cause unequal development of heat in the respective-windings. The windings may also have equal amounts of heat developed therein, but, because of diflerences in the respective sizes and in the radiation constants, the heat may be unequally radiated, or

the resulting temperatures, with consequent changes in resistance, may be different due to the difi'erence in the size and mass of the respective windings. Moreover, the windings vmay be equally heated and have equal radiation constants, but have difierent temperature resistance co-eflicients which will disproportionately change the values of the resistance of the respective windings. The variations in the resistance of the windings that maybe caused by the heating thereof will so readi'ust the respective ma netizing forces deve oped thereby as to su ciently unbalance the forces to efiect the operation of the relay.

The windings and 11 may also be so calibrated, that, below a redetermined temperature therein, the win ing 11, that is disposed on the portion adjacent the contact members, may produce a magnetic force slightly greater than the force of the winding 10 to ensure a more positive engagement of the contact members. As the predetermined temperature isattained, the two forces equalize, and, when a second predetermined temperature of greater value is attained, the force that is produced by the winding 10 may increase to a value t at is sufiicient to operate 2 of the win ing 11 and of the spring 9.

Although I have shown several forms of. relays embodying my invention, I do, not limit them to the specific structures that are illustrated since various modifications may be made therein within the spirit and scope of the inventionasset forth in the appended claims.

I claim for my invention; 1. A thermal relay for an electric circuit comprising a magnetizable element provided with two llnked magnetic circuits, means energized from the electric circuit-for setting up opposing magnetic forces in the respective the relay a ainst the combined counter forces 4. A relay comprising a movable armature,

means windings for respectively moving said armature in two directions, the magnetic efiects of saidwindings on said armature being normally in opposition and said windings havcluding two parallel-connected ing difierent temperature coeflicients of resistance.

5. A relay comprising a movable member, a winding t erefor for influencing said member in one direction and a shunt winding for the first-named windin to influence said member in an o posite 'rection, said windings havin di erent coeflicients of resistance, where y actuation of the movable member may be effected at a predetermined temperature of the windin s.

In testimony whereo I have hereunto subscribed my name this 29th da of Jul 1920.

OLIVER S. dEN GS.

comprising a biased circuit-controlling member, and means for establishing two magnetic forces for actuatin the controlling member in one or another aving such temperature-resistance characteristics as to actuate the control member 1n rection, said means comprising two difierentially efiective windings one direction until a temperature is attained therein indicating a den erous condition in 6 therewith an pivotally mounted on the can the associated circuit an toactuat'e the con- E-sha an armature cooperatmg liu 

